Police said most of the victims in Friday's shooting were Vietnamese attending a citizenship class in upstate New York.
Police cordon off American Civic Association building in Binghamton
Pakistan's top Taliban commander Baitullah Mehsud Saturday claimed responsibility for the shootings at an US immigration services centre in the US state of New York that killed 13 people.
"I accept the responsibility. They were my men," Mehsud told reporters in Peshawar on phone from some undisclosed location.
Mehsud said the massacre was in revenge for the continued US drone attacks on Pakistan's tribal region bordering Afghanistan.
US officials were not immediately available for comment about Mehsud's claim, but Pakistani security analysts dismissed it as a publicity stunt.
Victims were attending immigration classes
The incident began mid-morning when a man, later identified as a Vietnamese immigrant, entered the American Civic Association building in Binghamton, around 200 kms northwest of New York City.
He opened fire, killing 13 people before taking more than 20 people hostage. The siege lasted a number of hours before the shooter was found dead in the building with a self-inflicted gunshot wound to his head.
US Vice President Joe Biden, speaking in New York City, said the gunman had targeted immigrants taking a citizenship class.
Local police chief Joseph Zikuski told reporters that the gunman had been "recently terminated from a job. He didn't speak English very well," and was feeling pretty low.
Police say the alleged gunman, believed to be a Vietnamese migrant, had recently been sacked by computer giant IBM.